If you stare at the black + in the center, the moving dot turns t! ! o green .
Now, concentrate on the black + in the center of the picture. After a short period of time, all the pink dots will slowly disappear, and you will only see a green dot rotating.
It's amazing how our brain works. There really is no green dot , and the pink ones really don't disappear. This should be proof enough, we don't always see what we think we see .